The present invention relates to a shifting arrangement for an automatic transmission of a motor vehicle controlled by an electronic control apparatus, which includes a selector lever by the displacement of which in a first shifting lane the different transmission speeds to be automatically shifted are preselectable.
Such a transmission is described in the Bosch Techn. Berichte [Bosch Technical Reports] 7 (1983)4, page 160 to 166. The drive takes place by way of a hydrodynamic torque converter which serves as starting coupling and for the purpose of moment transmission. The torque converter can be bridged by means of a bridging or by-pass clutch and a rigid drive to a series-connected four-speed planetary gear transmission can be established. The transmission output rotational speed, the load condition of the engine, the engine rotational speed as well as the position of the selector lever are detected by sensors and are fed as electrical magnitudes to an electronic control apparatus. The respective optimum transmission speed is determined from these informations according to a predetermined computer program and is hydraulically engaged by the control apparatus by way of electromagnetic transmission-speed-shifting valves in the transmission. Three shifting programs are selectable by the driver on a program switch: an economy program for a particularly economic driving manner, a power program for sporty driving and a program with manual adjustment of the respectively desired transmission speed by way of the selector lever. According to a further development, the first two programs are integrated into the electronic control apparatus which, for this purpose, has been enlarged by control units that need not be explained in detail herein.
It is the object of the present invention to make realizable the program: manual speed selection by means of the selector lever, in order to be able to dispense with the program switch and thus to constitute the transmission more friendly as regards operation and more favorable as regards manufacture.
The underlying problems are solved according to the present invention in that the selector lever is adapted to be shifted by way of a transverse lane into a second shifting lane parallel to a first shifting lane, and in that by displacement in the second shifting lane the forward speeds of the transmission are manually engageable by means of the selector lever. A particularly advantageous construction of the present invention is realized if a shifting-up by one speed is manually engageable by a single displacement of the shifting lever in the second shifting lane from a neutral center position thereof and by contacting a plus sensor in the one direction and if a shifting-down by one speed is manually engageable by a single displacement of the shifting lever in the opposite direction and by contacting with a minus sensor whereby the shifting lever is automatically returned into the neutral position after each displacement. Furthermore, a particularly favorable arrangement is realized in that the first shifting lane extending in the driving direction, the second shifting lane and the cross lane are provided in a cover plate which, together with a left lateral part and a right lateral part and a bottom plate form a hollow frame secured at the body of the vehicle. If for the manual speed shifting the selector lever is constructed as rocker-type lever which during pivoting through about 5.degree. from its neutral central position in the one direction causes a shifting-up by one speed and in the other direction a shifting-down by one speed, then the driver can engage the transmission speeds rapidly and effortlessly. A brief tipping of the selector lever in one of the directions suffices in order to shift the transmission by one speed. Thereafter, the rocker lever automatically returns into the neutral position. When tipping the rocker lever twice, a shifting-up or shifting-down by two speeds takes place. In the selected four-speed transmission, a shifting-up or shifting-down maximum by three speeds can take place by tipping the shifting lever three times. The present invention also offers advantageous constructive realizations of the selector lever and its bearing support in the hollow frame of the vehicle body.